[gcc r13-2914] LoongArch: Use UNSPEC for fmin/fmax RTL pattern [PR105414]

[Xi Ruoyao <xry111@gcc.gnu.org>]

https://gcc.gnu.org/g:b48d7ff3570fa0ebe7790275cf020d8885120338

commit r13-2914-gb48d7ff3570fa0ebe7790275cf020d8885120338
Author: Xi Ruoyao <xry111@xry111.site>
Date:   Sat Sep 24 20:47:22 2022 +0800

    LoongArch: Use UNSPEC for fmin/fmax RTL pattern [PR105414]
    
    I made a mistake defining fmin/fmax RTL patterns in r13-2085: I used
    smin and smax in the definition mistakenly.  This causes the optimizer
    to perform constant folding as if fmin/fmax was "really" smin/smax
    operations even with -fsignaling-nans.  Then pr105414.c fails.
    
    We don't have fmin/fmax RTL codes for now (PR107013) so we can only use
    an UNSPEC for fmin and fmax patterns.
    
    gcc/ChangeLog:
    
            PR tree-optimization/105414
            * config/loongarch/loongarch.md (UNSPEC_FMAX): New unspec.
            (UNSPEC_FMIN): Likewise.
            (fmax<mode>3): Use UNSPEC_FMAX instead of smax.
            (fmin<mode>3): Use UNSPEC_FMIN instead of smin.

Diff:
---
 gcc/config/loongarch/loongarch.md | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
index 3787fd8230f..214b14bddd3 100644
--- a/gcc/config/loongarch/loongarch.md
+++ b/gcc/config/loongarch/loongarch.md
@@ -35,6 +35,8 @@
   ;; Floating point unspecs.
   UNSPEC_FRINT
   UNSPEC_FCLASS
+  UNSPEC_FMAX
+  UNSPEC_FMIN
 
   ;; Override return address for exception handling.
   UNSPEC_EH_RETURN
@@ -1032,8 +1034,9 @@
 
 (define_insn "fmax<mode>3"
   [(set (match_operand:ANYF 0 "register_operand" "=f")
-	(smax:ANYF (match_operand:ANYF 1 "register_operand" "f")
-		   (match_operand:ANYF 2 "register_operand" "f")))]
+	(unspec:ANYF [(use (match_operand:ANYF 1 "register_operand" "f"))
+		      (use (match_operand:ANYF 2 "register_operand" "f"))]
+		     UNSPEC_FMAX))]
   ""
   "fmax.<fmt>\t%0,%1,%2"
   [(set_attr "type" "fmove")
@@ -1041,8 +1044,9 @@
 
 (define_insn "fmin<mode>3"
   [(set (match_operand:ANYF 0 "register_operand" "=f")
-	(smin:ANYF (match_operand:ANYF 1 "register_operand" "f")
-		   (match_operand:ANYF 2 "register_operand" "f")))]
+	(unspec:ANYF [(use (match_operand:ANYF 1 "register_operand" "f"))
+		      (use (match_operand:ANYF 2 "register_operand" "f"))]
+		     UNSPEC_FMIN))]
   ""
   "fmin.<fmt>\t%0,%1,%2"
   [(set_attr "type" "fmove")